Патент USA US2407460код для вставки
-Sept.1o,v194e. f B. VAN RYN » 2,407,460 SWITCH FOR HIGH FREQUENCY CIRCUITS Fílèd Hay 15, 1943 BC I ' ,f0. . l , l É I | a 613 / ,Q ' . l I l | GROUNDED SII/E10 BERNARD vn/v ,Q YN A TTOR/VEY 2,407,460 Patented Sept. 10, 1946l UNITED’STATES PATENT OFFICE 2,407,460 SWITCH FOR HIGH-FREQUENCY CIRCUITS Bernard van Ryn, Chelmsford, England, assign or to Radio Corporation of America, a corpora tion of Delaware Application May 15, 1943, Serial No. 487,426 In Great Britain April 2, 1942 4 Claims. v (Cl. 179-1715) 2 1 impedance to radio-frequency energy, a source of direct current energy, and a switch for con rangements for electric circuits carrying radio necting said source to the anode (or element serv frequency energy and particularly for radio-fre ing as anode) of said rectifier in such sense as to quency oscillators. . ~ It is frequently required that a circuit carrying Ul cause said rectifier to become conducting so' as to present a low impedance vto radio-frequency radio-frequency energy, such as an oscillator 'I‘he present invention relates to switching ar valve having a radio-frequency output, shall be Y energy. If desired, there may be connected between screened so that it shall not cause interference with other apparatus, and yet that access shall be available to the circuit for the purpose of switch said anode and said switch, a. radio-frequency fil- l ter comprising a series-connected resistor or in ing it out of operation. ` As a case inpoint, mention may be made of a Fig. 1 of the accompanying drawing illustrates ductor and a shunt-connected condenser.` a particular exemplary circuit arrangement for a superheterodyne receiver in which a beat fre telephone and continuous wave (C. W.) telegraph reception in which it; is important that as few 15 quency oscillator is employed for continuous wave (telegraph) reception; vand valves shall be used as conveniently possible and superheterodyne radio receiver designed for bo-th FigfZ shows arcircuit diagram of an alternative in which, to this end, the first audio-frequency . amplifier stage and the beat frequency oscillator embodiment. vention to such a case. ' quency from reaching, by external coupling, earl . ~ valve, which may be a triode, has its cathode con nected to >ground through a condenser-shunted In a case such as that outlined above, in o-rder ` to prevent any of the harmonics of the beat fre-v .. Referring to Fig. 1, a common valve V is used to function as the- first audio-frequency amplifier (A. F. amp.) and as the beat-frequency oscilla. tion generator (B. F. O.) ofthe receiver.` The share in common a single valve. It is to be under stood that a case of this nature is to beregarded merely as exemplary and not as limiting the in 25 bias resistor BR and its anode connected to the control grid -througha variable condenser C2, inv ier stages of the receiver, .it is usual to mount the series with a further condenser C3, which may or may not be variable, and a parallel-tuned circuit v Valve serving the two purposes mentioned in a separate screening box. - TC.y The anode fof the Valve'ís also connected, For the reception of modulated waves (tele phone reception), however, it is required to switch 30 through a radio-frequency choke HFC in series with an audio-frequency choke LFC to the posi off the beat vfrequency oscillator without, in any tive terminal HT-i- ofthe usual source of high Way, interfering with the performance of the potential energy (not shown), the negative ter valve insofar as its audio-frequency amplifying functions are concerned. Such a switching oper mina-l of which is,.as is usual, grounded or other ation would present no problem were it possible ' wise connected to the cathode of the valve. ` , Audio frequency input is applied fromthe out or permissible, as frequently it is not, to mount the necessary switching apparatus within the box which contains the valve and the immediately put of the second detector, represented by block D, to some convenient point on the inductor L of associated complementary instrumentalities andv ' the vparallel-tuned circuit TC through a radio fre quency choke HFC?` between the grid end of which elements. The diñîculty presented, when such mounting within the box is not possible or per missible, could of course be overcome by mount ing the switch outside the box and bringing a lead from the inside of the box tothe switch. Since, however, such a lead would be carrying radio 45 frequency energy, it and the switch to'which'it vis to be connected would have to be screened, 'a con dition which, under certain circumstances, >as when the switch is' required to perfo-rm other functions, presents its own problems. According to the invention, a switching ar rangementfor 'a circuit, vor circuit element, carry ing radio-frequency energy includes,'co-nnected„ and ground there is connected a radio frequency bypass condenser RFC. Audio frequency output may be taken from a lpoint between the two chokes HFCand LFC and fed through a block ing condenser BC to the final audio stage, repre n sented by block O. Thefswitching device'according to the inven tionis connected to a point X between the series connected variable condenser C2 and the con denser C3, and comprises a rectifier W connected between this point and gro-und, a resistor'R con nected betweenfthis. same point (that is, effec tively, between one'terminal ofthe'rectiñer) and one terminal of a make-,break switch S, the'other across the circuit or circuit element, a rectifierl which in its normal condition presents a .highA 55 terminal of >which is connected tothe -positive ter 2,407,4ec 3 4 minal HT+ of a source of energy, and a decou LFC, to the positive terminal HT+ of the usual pling condenser Cl connected between the said source of high-tension energy (not shown), the negative terminal of which is, as is usual, ground one terminal of the switch and ground. The rectiñer W is so connected that when the ed or otherwise connected to the cathode of the switch is closed to condition the tube as the beat valve. frequency oscillator for C. W. reception the posi Audio-frequency input is derived from a point tive terminal l-IT-l- of the source of energy, which source may be the same as that connected to the anode of the valve V, is connected to that termi-l on the low-frequency volume control resistor LR and applied over lead AI to some convenient point Y on the inductor L of the parallel-tuned circuit nal of the rectifier which is connected to the junction point X of the series connected condens ers. The rectifier therefore will be> conductive l , and will provide a path of low impedance between 1, the said point and ground. By way of further explanation or" the operation of the system disclosed in Fig. 1, tube V operates, ' for the reception of radio telephony (voice), onlyas an audio frequency amplifier, and for the re Y TC, and audio-frequency output may be taken from a point between the two chokes HFC and LFC and fed through a blocking condenser BC to the final audio stage, represented by block O‘. The switching device according to the inven tion is connected to a point X between the series connected variable condenser C2 and further condenser C3, and comprises diode portion DI of the double-diode-triode valve V connected be ception of radio telegraphy (code) it operates as> " tween this point and ground, a resistor R oon a combined audio frequency amplifier and beat - nected between this same point (that ineffective ly, between one terminal of the rectifier) and one terminal of a make-break switch S, the other ter minal of which is connected to the positive termi frequency' oscillator. In the latter instance; switch S will be closed and tube V will function as a Hartley oscillator by reason of the connection of the grid to one side of the frequency determin nal I-lT-i- of a source of energy, and a decoupling ing circuit TC, the connection of the anode condenser Ci connected between the said one ter through closed switch S, resistance R and con- V minal of the switch and ground. , y denser C3 to the other side of circuit TC, and the The diode portion DI is so connected, that connection of the cathode through condenser when the switch S is closed, the positive» terminal RFC to an intermediate point on the coil L of HT+ of the source of energy, which source may be the same as that connected tothe anode> of the valve V, is connected to the anode of the di ode, the diode is conductive and provides a path circuit TC. ' ‘ Audio frequency signals from the seco-nd detecH tor D are also applied to the grid of tube V by way of the tapped connection on circuit TC which for audio frequency is connected to ground through condenser C3 and the rectifier W which it will be remembered provides a path of low impedance in the closed position of switch S. The heterodyne beat resulting from 'the interac tion in tube V of the audio frequency signals and of low impedance between the point X and ground. The other diode D2 serves as a detector and also supplies anv AVC bias voltage Vto the lead AVC. ' The resistive value of the `resistor R may be quite high (for example 2 megohms) and'it and the decoupling condenser CI then constitute a the output of the tube and be amplified and in satisfactory radio-frequency filter so that the lead beyond this filter, and the switch, will be at dicated in the usual manner. substantially zero radio-frequency potential. the locally produced oscillations will appear in . As heretofore ex plained the radio frequency filter constituted by R and Cl prevents thefoscillations of the beat frequency oscillator from being transmitted to earlier stages of the receiver through the switch Sand its connections. ' ' i ' For the reception of radio telephony, the open ing of switch S removes the voltage from across rectifier W which therefore acts as a high imped ance device, and being shunted effectively across the space discharge path of the tube prevents the tube from oscillating. The tube and associated circuit elements (TC, BR, LFC and BC) will how l. A circuit arrangement comprising a tube provided at least with a cathode, control grid and anode, two condensers and a tuned circuit con nected in series and in the order named between said anode and control grid, the cathode being connected to ground, means for coupling a source of audio frequencies to said tuned circuit, a recti ñer so connected betweeen the- junction point of said oondensers and ground as to present a high impedance to radio frequency energy and to thereby condition the tube to ,function as an audio ever function as an audio frequency ampliñer. The rectifier may be a dry-plate rectifier, as illustra-ted in Fig. 1, or a diode, or a triode acting as such, or it may be the diode-portion of a di ode-triode, or, as illustrated in Fig. 2 of the ac - frequency ampliiienand a switch for connecting companying drawing, one of the diode-portions of a double-diode-triode, the other diode-por tion in this circuit serving for detection and for the production of ‘an automatic volume-control bias. Referring to Fig. 2, the triode part of the valve 2. A circuit arrangement as claimed in claim 1 wherein 'there is connectedacross said rectifier a resistor and condenser in series, said switch be ing connected on one side to the junction of said resistor 'and condenser and on~ the other side to V serves as a beat-frequency oscillato-r and audio frequency amplifier. The cathode of the valve is connected to earth through a condenser-shunted bias resistor BR and the anode is connected to the-control grid of the valve through a variable condenser C2, in series with a further condenser C3, which >may or may not be variable, and a par allel-tuned circuit TC. The anode of the valve is a potential across said rectifier to reduce theim. pedance of said rectiñer for radio frequency and, to thereby condition the tube to function as an oscillation generator. f the positive terminal of a source of current, said resistor and condenser' constituting a radio fre quency filter to prevent radio frequency being transmitted to said switch and its connections. Y 3. A circuit arrangement as claimed in Vclaim 1 wherein said rectifier is a diode. , 4. A circuit arrangement as claimed in claim l wherein said tube is a diode-triode'and the recti iier constitutes the` diode portion of the tube. also connected, through a radio-frequency‘choke HFC in series with an audio-frequency choke BERNARD VAN RYN.